The I-61 (not the L/D) is much better machined and finished lens than the L/D. In fact, the I-61L/D looks somewhat cheap and tinny in comparison.
The stiffness is easy to fix by partially disassembling and lubing the focusing helical. The disassembly is somewhat different than the L/D, and is identical to the I-26M and some of the Jupiter-8's.
Matt Denton's site has instructions for doing this.
http://homepage.mac.com/mattdenton/p...ras/index.html
-Paul